There are two main objectives for this project (1) synthesis of keto unsaturated nucleosides of (a) 5-fluoro-cytosine (b) cytosine (c) 5-trifluoromethyl uracil and (d) 5-iodouracil (2) to do a biological evaluation of these nucleosides to find the extent of anticancer activity of these unsaturated ketonucleosides. Investigations in our laboratory have unequivocally shown that unsaturated keto nucleosides of 5-flurouracil with alpha-L-rhamnose inhibit significantly the growth of the following cancer cell lines: murine leukemia (L1210), murine mammary carcinoma (FM3A), human B-lymphoblast (Raji) and human T-lymphoblast (molt/4F). Alpha-L-rhamnose and alpha-L-fucose are biologically important sugars with fairly close structural relationship. It is therefore hypothesized that unsaturated keto nucleosides of alpha-L-fucose also will show significant anticancer activity. Methodology in arriving at the target compounds is a modified procedure adopted from the standard nucleoside synthesis. It involves coupling the silylated base with peracetylated sugar to get the protected nucleoside. Later steps involve deprotection and protection with appropriate groups. In vitro and in vivo evaluations will be done on these unsaturated ketonucleosides.